As I posted previously - if in fact there was a 3825 (even one FXO capable) at the BC residence that connected to Cisco on 7/11...this is not a smoking gun.
By October, which is when the SW for routers, modems and phones was issued, BC already knew that NC friends were directing CPD to look into the possibility that he spoofed calls - it reasons that he (innocent or guilty) would not cooperate in the discovery of self-incriminating evidence.
More importantly, why would he use that behemoth piece of equipment to connect to Cisco on 7/11 and then spoof a call the next day when he didn't need it to connect to work, and could have spoofed a call in a really "low tech" way?
If BC is guilty, why would he even need to create an alibi to 'prove' NC was alive at 6:40? How would BC know at that time that pinpointing NC death to earlier in the evening would be crucial to the prosecution? Even if he did, he could have just as easily said, "I was back and forth to HT for groceries and NC was home with the kids. I wouldn't leave them home alone."